1. Field of the Invention
The present invention relates to a radio terminal belonging to a radio network for carrying out communications by setting up logical channels on a radio network in advance and an information transfer method of a radio terminal, as well as to a radio gateway device for connecting an IEEE 1394 bus with a radio network for carrying out communications by setting up logical channels on a radio network in advance and an information transfer method of a radio gateway device.
2. Description of the Background Art
In recent years, the realization of home network is attracting much attention, and in particular, the IEEE 1394 bus for connecting between digital home electronic devices has been attracting considerable attention. The IEEE 1394 bus is capable of connecting a plurality of IEEE nodes in daisy chain or star connection and transferring a wideband data in excess of 100 Mbps. Also, it has a major feature that it is possible to transmit both asynchronous data and isochronous data on the same cable. For this reason, even though the IEEE 1394 bus was originally developed as a next generation version of SCSI, there are increasing trends to use the IEEE 1394 bus as a cable for connecting AV devices.
On the other hand, the realization of fast radio network (radio LAN) is also attracting attention. In particular, since the determination of the IEEE 802.11 specification in 1998, many radio LAN products are appearing in the market and there has been a remarkable decrease in the prices of these radio LAN products.
In conjunction with this trend for improved performance and reduced cost of the radio technology, there is an active trend to consider applications of the radio technology to the home environment and this trend is expected to grow further in future as can be anticipated by establishment of organizations of related companies such as HomeRF and Bluetooth (a kind of radio system using 2.4 GHz band) in the U.S.A. Also, from a viewpoint of the home network, the radio system is an easily acceptable system as it does not require any new cable construction. For this reason, a network system merging the IEEE 1394 bus and the fast and inexpensive radio LAN system is expected to play a central role in the future home network.
In such an environment for merging the IEEE 1394 bus and the radio network, there are several outstanding problems.
For example, one of the problems is how a protocol executed on the IEEE 1394 bus (a protocol presupposing the IEEE 1394 at the datalink layer such as AV/C protocol) can be executed over the radio network. In particular, in the case of executing a protocol such as the AV/C protocol in which message types (command, response, etc.) on the protocol are identified by logical addresses (registers) on the IEEE 1394 bus (where a value indicating an AV/C command or a value indicating an AV/C response can be found by reading a register according to an offset value described in a packet), identifiers corresponding to the logical addresses on that IEEE 1394 bus must also be provided at the radio LAN side. This situation is similar in the case of executing the AV/C protocol or the like between radio terminals.